1. Field of the Invention
The present invention relates to a method of producing (S)-4-hydroxymethyl-.gamma.-lactone represented by the following chemical structural formula 10. ##STR1##
2. Description of the Related Art
(S)-4-hydroxymethyl-.gamma.-lactone 10 is a useful raw material for synthesizing various kinds of nucleic acids. The nucleic acids are excellent fodder additives, and some of then are even useful as medicines.
In order to synthesize (S)-4-hydroxymethyl-.gamma.-lactone 10, the below-illustrated method, which begins with glutamic acid as the starting material, is presently known (J.Org.Chem.,Vol.53, No.20, p4781(1988)). ##STR2##
However, this method has the following problems:
As illustrated above, in the first step of this method, glutamic acid 1 is subjected to deamination, and thus forming crystalline intermediate 2. Since the retention of the stereochemistry of the intermediate 2 during this reaction is not sufficient, the intermediate partially becomes a recemate. Since the reaction proceeds via this intermediate 2, it is extremely difficult to obtain, the (S)-4-hydroxymethyl-.gamma.-lactone 10, with the high optical purity.
Further, the yield of intermediate 2 from glutamic acid 1 is 56%, and the yield of (S)-4-hydroxymethyl-.gamma.-lactone from intermediate 2 is no more than about 63%. Therefore, the yield of the objective material 10 as a result is extremely low.
Moreover, since the crystalline intermediate 2 is soluble to water, it is very difficult to isolate it, and the procedures thereof is very complicated.
In addition, since not only because of its low yield, but also because of the high price of the raw material, namely glutamic acid, the cost of the product becomes very expensive.